Error-compensation model for simultaneous measurement of five degrees of freedom motion errors of a rotary axis

This paper introduces an error-compensation model for our measurement method to measure five motion errors of a rotary axis based on fibre laser collimation. The error-compensation model is established in a matrix form using the homogeneous coordinate transformation theory. The influences of the installation errors, error crosstalk, and manufacturing errors are analysed. The model is verified by both ZEMAX simulation and measurement experiments. The repeatability values of the radial and axial motion errors are significantly suppressed by more than 50% after compensation. The repeatability experiments of five degrees of freedom motion errors and the comparison experiments of two degrees of freedom motion errors of an indexing table were performed by our measuring device and a standard instrument. The results show that the repeatability values of the angular positioning error epsilon(z) and tilt motion error around the Y axis epsilon(y) are 1.2 '' and 4.4 '', and the comparison deviations of the two motion errors are 4.0 '' and 4.4 '', respectively. The repeatability values of the radial and axial motion errors, delta(y) and delta(z), are 1.3 and 0.6 mu m, respectively. The repeatability value of the tilt motion error around the X axis epsilon(x) is 3.8 ''.